1) Field of the Invention
The present invention relates to a centrifuge such as a centrifugal separator, and more particularly to a means for detecting an abnormal condition of a centrifuge.
2) Description of the Related Art
So far, there have been known various types of swing rotors for use in centrifuges, and as a general type, cylindrical rotor pins, which function as supporting points for swinging, are set on both side surfaces of a bucket for accommodating a sample or specimen and the bucket is mounted through these rotor pins to arm portions of the rotor. The rotor pins are located on the swing axis and are usually fixedly secured either to the rotor side or to the bucket side. The rotation of the rotor produces a centrifugal force to lift the bottom surface of the bucket, thereby enabling the swinging motion. During swinging, sliding occurs at pin side surfaces between the rotor pins and the pin bearing portions of the bucket, which requires frequent and periodical application of a lubricant or the like thereonto for the purpose of achieving secure swinging operations.
In the case of the swing rotor, because of the occurrence of the sliding phenomenon between the rotor pins and the pin bearing portion of the bucket as mentioned above, there is a possibility that the bucket stops halfway due to a friction therebetween so that the bucket does not return to the original position, that is, it does not return to a vertical condition, when the rotation of the rotor comes to stop. If a sample container is not in a covered condition, the sample can spill in the stopping condition. In addition, in the case of an automatic centrifuge in which a sample is automatically taken in and out, difficulty is frequently experienced in taking out the sample when the bucket does not return to the original position, thus leading to a loss of the sample or damages to the apparatus.
It is therefore an object of the present invention to detect abnormal conditions prior to the occurrence of the above-mentioned troubles for protecting a sample and apparatus, and further to enable maintenance of the apparatus in advance.
For this purpose, sensor means is provided to detect apparatus conditions including a stop of a rotor and a posture or position of a bucket prior to the stop of the rotor.
The sensor means is made to detect the posture or position of the bucket when the rotor is in a stop condition or in a low-speed rotation condition, and if the sensor means cannot detect the presence of the bucket, a decision is made that an abnormality of the swinging movement of the bucket has occurred, and the fact of the occurrence of the abnormality is notified to a user of the centrifuge. Moreover, if at least one of the sensor means detects the presence of the bucket when the rotor is in a rotation condition, a decision is made that the sensor means falls into an abnormal condition.
For connection of the bucket to the rotor, the holding position of the bucket is set to exist inwardly with respect to the center of gravity of the bucket in a radial direction of the rotor in a state where the bucket is in a stop condition.
A stopping member is provided inwardly with respect to the bucket to stop or bear the bucket to maintain the bucket at a vertical position when said rotor is in a stop condition or rotates at a speed below a predetermined value.